A substrate deposition system may be used to process a substrate with an energized gas, such as plasma. Typically, the system includes a deposition chamber which encloses a process zone into which a gas is introduced, a gas energizer to energize the gas, and an exhaust to remove the energized gas. The deposition chamber may, for example, be used to deposit material on the substrate.
The chamber components exposed to the energized gas are often covered with removable shields which protect the surface of the chamber components from the sputtered residues used to deposit material on the substrate. The sputtered material coats the shield which can be removed and replaced when the layer reaches a thickness such that particles begin to flake off and contaminate the process chamber. In subsequent processing cycles, the deposited process residues can flake off of the shield surfaces and fall upon and contaminate the substrate. Therefore, the shields must be frequently periodically removed and cleaned of surface residue. Manufacturers often use sandblasting to roughen the shield, which allows them to run the sputtering chamber for longer periods of time with out a shield change, reducing the down time of process equipment. However, sandblasting leaves particle residue on the surface of the shields which can increase the chances of contamination of the substrate.
U.S. Patent Application Publication No. 2005/0089699 to Lin et al. relates to a method for cleaning and refurbishing process chamber components, such as a chamber shield having a coating. The method includes immersing the shield in an acidic cleaning solution, such as HF, HNO3, HCl, H3PO4, and H2SO4, and/or a basic cleaning solution, such as KOH, NH4OH, NaOH, and K2CO3, to remove process surface residue and clean or remove at least a portion of the coating of the shield. Optionally, the chemically cleaned surface can be further cleaned by performing an ultrasonic cleaning step followed by heating. The shield is then subject to a penetrative grit blast, using particles having a grit mesh size of about 80 to 120, to remove compounds between the underlying structure and the coating. The cleaned surface is then subject to a texturizing grit blast, using particles having a grit mesh size of about 24 to 70, to provide a surface roughness of about 150 to 350 microinches. Optionally, the texturized surface can be further cleaned by performing an ultrasonic cleaning step followed by heating. Once the surface of the shield has been cleaned and textured as set forth above, a metal coating is applied by a deposition process. The refurbished shield has coating having a thickness of about 152 to 508 microns and a surface roughness of about 1000 to 2000 microinches.
Thus, it is desirable to provide a process for cleaning coated shields which minimizes the amount of flake-off of process residue. It is further desirable to deposit low defect films on substrates and provide a process for cleaning coated shields resulting in a high surface roughness and low particle residue.